Genetic diversity and adaption Flashcards
what is genetic diversity?
the number of alleles of genes in a population.
what is genetic variation
small differences in DNA base sequences, transfered between generations and leads to genetic diversity
what is the effect of mutations?
generates new alleles and contriutes to genetic diversity.
What are the effects of genetic diversity
it is a necessity for natural selection to occur.
differences in alleles leads to differences in phenotypes
what is selection pressure and what does it do?
factors which affect the chance of survival of an organism.
increease the chance of individuals with a specific phenotype surviving and reproducing over others.
individuals with favoured phenotypes, what are their charictaristics and privaliges.
has higher fitness
this is defined by it’s ability to survive and pass on its alleles to offspring.
organisms with higher fitness posses adaptions that make them better suited to their environment.
effect of a large gene pool or high genetic diversity.
strong ability to adapt to change.
effect of a small gene pool
less able to adapt to change, vunerable to extinction.
what is natural selection?
selection pressures produce a graducal change in allele frequencies over several generations.
genetic drift
gradual change in allele frequencies in a population due to chance and not natural selection.
Stabilising selection
natural selection
keeps allele frequenacies relatively constant over generations
things stay the same unless environment changes.
extremes are selected against leading to mainainance of the intermediate
e.g. birth weights
Directional selection and 3 causes.
gradual change in allele frequencies over several generations
usually happens when there is a change in environment/selection pressure or a new allele has appearen in the pop that is advantagous.
e.g. antibiotic ressistance of bacteria
what is a selection pressure?
environmental factors which affect chance of survival of an organism.
what do selection pressures effect.
allele frequencies of a pop through natural selection
adaptions
This is because the environment has changed
what are the types of adaptations? 3 and explain
APB
Anatomical
structural/physical feature
e.g. white fur of polar bear provides camouflage in snow. less chance of detection.
Physiological
Biological processes within the organism.
e.g. mosquitos produce chemicals that stop the animal’s blood clotting when they bite, this helps to feed more easily.
Behavioural
the way organisms behave.
e.g. cold blooded reptiles bask in the sun to absorb heat.
